What’s Vulnerable › Vulnerabilities

CVE-2020-12406

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-07-09 · updated 2026-06-17
• Weakness: CWE-345

Description

Mozilla Developer Iain Ireland discovered a missing type check during unboxed objects removal, resulting in a crash. We presume that with enough effort that it could be exploited to run arbitrary code. This vulnerability affects Thunderbird < 68.9.0, Firefox < 77, and Firefox ESR < 68.9.

Affected products

• Canonical Ubuntu Linux: 16.04, 18.04, 19.10, 20.04
• Mozilla Firefox: before 77.0 — fixed in 77.0
• Mozilla Firefox ESR: before 68.9.0 — fixed in 68.9.0
• Mozilla Thunderbird: before 68.9.0 — fixed in 68.9.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 77.0; Mozilla Firefox ESR 68.9.0; Mozilla Thunderbird 68.9.0. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1639590
• https://usn.ubuntu.com/4421-1/
• https://www.mozilla.org/security/advisories/mfsa2020-20/
• https://www.mozilla.org/security/advisories/mfsa2020-21/
• https://www.mozilla.org/security/advisories/mfsa2020-22/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1639590
• https://usn.ubuntu.com/4421-1/
• https://www.mozilla.org/security/advisories/mfsa2020-20/
• https://www.mozilla.org/security/advisories/mfsa2020-21/
• https://www.mozilla.org/security/advisories/mfsa2020-22/

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